textproduct: Quad Cities

KEY MESSAGES

- Multiple rounds of repeating storms tonight through Wednesday, with heavy rain likely. Rain amounts between 1-2", with localized 3" totals possible leading to a flash flood threat.

- There is a Marginal (level 1 out of 5) risk for severe weather Wednesday. The primary hazards will be heavy rain and gusty winds.

- Dry conditions late week and into the weekend, with a return to active weather next week along with a warming trend.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 206 PM CDT Tue Aug 4 2026

Typical summer weather was seen outside today, with 1pm temperatures in the 80s and dewpoints in the upper 60s/low 70s making it feel a tad humid outside. A weak cold front was pushing southeast over eastern IA and even showing up on radar just south of DBQ extending southwest between CID and IOW. Scattered showers were seen behind the front, with a SCT-BKN deck of clouds keeping our northwest 1/4 of the CWA slightly cooler today. Another shortwave over the central Plains was aiding in shower/thunderstorm development over eastern NE.

Late Afternoon/Evening:

The aforementioned cold front to stall out near or just south of I-80, with scattered showers moving into eastern IA. GOES satellite imagery shows clearing ahead of the front, however, our 18z sounding has a very strong cap rooted at 800mb (~6kft) with very weak deep layer shear. While some CAMs (HRRR/NamNest/RRFS) show storms over eastern IA late this afternoon and evening, my current thinking is that the cap will hold and keep most if not all storm activity at bay until late evening/overnight. IF a storm were to break the cap, with DCAPE values around 1100 J/Kg and steeping mid level lapse rates some gusty winds, small hail, and heavy rain would be possible. The SPC has a marginal (level 1 out of 5) risk for severe this afternoon. In addition rain shower coverage should also be quite limited, due to the dry mid-level profile on our 18z sounding.

Late Evening/Overnight through Wednesday:

The shortwave over NE will track east across IA, riding along the frontal boundary. Strong 850mb moisture transport and PWs over 2" combined with increasing low level convergence and large scale ascent to support multiple rounds of showers and embedded thunderstorms through the overnight hours. Forward propagating Corfidi vectors are progged to be aligned parallel with the surface boundary leading to a growing concern for training. Repeating rounds of storms with rainfall rates over 1"/hr per 16z RRFS could lead to localized flash flooding tonight, especially over urban areas and locations that saw the heaviest rain last week. However, confidence where the axis of heaviest amounts (2+") will lay out remains low with solutions ranging from the Hwy 20 corridor all the way down to the Hwy 34 corridor in IA. In any case, rain amounts over 1" appear likely for a large portion of the CWA. A Flood Watch was considered, but decided against it at this time due to 1-hr FFG currently in the 2 to 2.5" range and the strength of LLJ tonight is not as strong to support 2+"/hr rain rates.

Rainfall will be ongoing during the morning hours Wednesday, with coverage decreasing by midday ahead of the next approaching wave. This system to bring the heaviest rain to our far south and any severe risk will be largely dependent on atmosphere recovery and if we see any clearing take place. In any case, the SPC has a marginal (level 1 out of 5) risk for severe storms along and south of Hwy 30. The primary hazards will be heavy rain and gusty winds although a tornado can't be completely ruled out.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 206 PM CDT Tue Aug 4 2026

Thursday-Friday...northwest flow aloft to bring dry conditions and seasonable temperatures. Highs in the 80s and lows in the low 60s is forecast. Some additional wildfire smoke may also start to make its way closer to the Midwest, leading to more hazy skies and perhaps some vibrant sunsets.

Friday Night-Sunday...a weak shortwave trough to move through early in the period and low PoPs (<30%) have been maintained. However, forecast soundings show a lot of dry air and this may end up just being an increase in clouds. Otherwise, the active storm track to remain further north over the upper Midwest as pieces of energy rotate around the Hudson Bay low. Latest NBM trends have also lowered PoPs Saturday and early Sunday and I suspect this trend will continue. The exception to this is the 06z GFS where a fast moving shortwave may track over southern WI and northern IL and bring a chance of showers to northwest IL on Sunday. Otherwise, a warming trend remains likely this weekend, as southerly low level flow advects in warmer and moist air (850mb temps rising to 20-21C). NBM trends in high temps Sunday have come down 2-3 degrees Sunday, likely attributed to the warm bias from the GFS with readings now solidly in the 80s. These temperatures combined with high probabilities (>70%) for dewpoints in the 70s will result in heat indices in the mid 90s to low 100s Sunday.

Sunday night-Tuesday...weather pattern to become active once again, as several shortwaves move around the edge of the flattening western upper ridge/heat dome. The timing and evolution of these waves will be key to storm chances and any severe/flash flood risk. With a warm and humid airmass in place, an MCS or two is not out of the question which would also throw a wrench into the temperature/humidity forecast.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 626 PM CDT Tue Aug 4 2026

Occasional showers and thunderstorms are expected late tonight into Wednesday morning (50-80%+), likely leading to periods of MVFR/IFR ceilings and visibilities. The rain/thunder coverage is anticipated to be highest between 08Z-14Z/Wed., with lingering showers likely after this time. Another round of showers and storms is possible Wednesday PM, most favored to the south and east of DBQ/CID.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.